The application relates to a wound dressing in the form of a bag enclosing fly maggots, having a porous wall made of plastic.
To treat chronic, poor-healing wounds, it is known to insert live fly maggots into the wound. For this purpose, preferably maggots of the blow fly, for example, of the Lucilia sericata, are used. The efficacy of the maggots is based on the wound cleaning (debridement), the anti-microbial activity and the stimulation of the wound healing. The digestive enzymes secreted by the maggots are substantially responsible for these effects.
The maggots can be inserted into the open wound as so-called free runners, an adhesive gauze net preventing them from escaping from the wound.
Today, an application of the maggots by way of a bag-shaped wound dressing in which the maggots are enclosed is preferred. The wall of the bag is porous so that the secretion secreted by the maggots can pass through into the wound and so that the dissolved necrotic tissue can enter the bag and can be taken up by the maggots. Such a wound dressing is known from the publication EP 1 020 197 B1.
In this known wound dressing, the wall is made of a fine-mesh net from polyamide (for example, nylon fibers) or polyester yarn having mesh widths of approximately 0.12 mm. The use of such wound dressings, which, for example, are marketed under the “BioBag” brand by the company Biomonde GmbH, Barsbüttel, Germany, is, for example, described in an article by G. Cazander et al., “Maggot therapy for wound healing . . . ,” Journal of Wound Technology, July 2009, pages 18-23. In order to prevent an adhesive bonding of the walls, a spacer, for example, in the form of a PVA sponge, is preferably inserted into the bag, as a result of which sufficient room is kept free for the maggots.
In this known wound dressing, the textile net of the wall has to be very fine-meshed so that the maggots do not widen the mesh and escape. This fine-mesh structure has a disadvantageous effect on the porosity of the wall and, for this reason, on the fluid permeability of the wall. For this reason, it has been attempted to surround the bag made out of the fine-meshed polyamide net by a polyvinyl alcohol wet membrane. Such a wound dressing has been offered under the designation of “VitaPad” by the above-mentioned Biomonde GmbH. The PVA coating, however, in addition reduces the porosity. PVA foam finds application as a hydro sponge as a healing-promoting wound dressing. Owing to the strong evaporation, the water content of the PVA material as a coating can however only prevent a drying-out of the maggots in the short-term. For this reason, the entire bandage has to be moistened three times daily to keep the maggots alive. Moreover, the PVA membrane has to be kept wet because the membrane hardens when drying, no longer conforms to the wound and, as the case may be, harms the wound edges. The frequent moistening makes the wound treatment time-consuming. The evaporative cooling lowers the temperature of the bandage and, for this reason, of the wound, which negatively influences the growth of the maggots and the healing of the wound. In particular, the growth of microbial pathogens, so called wet germs, is promoted by constantly keeping the bandage wet. Infections caused hereby represent a dangerous complication of the wound treatment. For this reason, the application of this wound dressing is problematic, for reason of which said wound dressing has meanwhile been withdrawn from the market.